1. Field of the Invention
The present invention relates to heat treatment methods for silicon-containing zirconia and, more particularly, to methods for producing a silicon-containing zirconia calcined body and a silicon-containing zirconia sintered body.
2. Description of the Related Art
Zirconia (ZrO2) is a ceramic material with properties including high melting and boiling points, high bio-compatibility, high chemical stability, high strength, high hardness, and high toughness. Zirconia has been widely used in different industries including mechanical, electronic, electromechanical, architecture, aerospace, and biomedicine industries.
The most common example of application of zirconia in the biomedicine industry is using a zirconia sintered body as a prosthetic dental material. According to a current industrial technique, a zirconia blank is calcined at a high temperature of 1300-1450° C., and a zirconia calcined body is obtained after cooling. Next, the zirconia calcined body is milled to a desired shape and is heated again at a high temperature of 1300-1450° C., obtaining a zirconia sintered body that can be used as the material for dental prostheses or dental crowns. However, calcination processing and sintering processing at the high temperature consum considerable energy and, thus, result in a high manufacturing cost. The manufacturing cost can be reduced if the temperature of the calcination processing or sintering processing is reduced. Furthermore, in order to adapt to the high temperature processing, the equipment for heat treating zirconia must fulfill special safety regulations and is, thus, expensive, causing a limitation to development in the related industry.
Furthermore, shrinkage ratio of zirconia is not good after calcination, such that the compactness of the zirconia calcined body can not be further increased. Thus, the zirconia calcined body, when used as the prosthetic dental material, could brake due to insufficient structural strength.